After the introduction of new potato varieties, as the years of cultivation increased, a noticeable decline in yield was observed. The plants became shorter, the tubers smaller, and the stems and leaves showed abnormal characteristics such as curling or shrinking leaves. This phenomenon is known as "degradation." The primary cause of this degradation is viral infection, which is an infectious disease transmitted by insects, mainly aphids, or through direct contact between leaves.
Viral infections can disrupt the plant's physiological processes, reduce its vitality, and lead to significant yield losses. In severe cases, production can drop by 70% to 80%, and in some instances, no marketable potatoes are produced at all. Globally, there are 18 known viruses that infect potatoes, including one virus and two types of mycoplasma. Among these, nine are specific to potatoes, while seven are commonly found in certain regions. These include PVX, PVY, PVS, PVM, PVMA, PVA, and PLRV. Additionally, some viruses that affect other crops like tobacco, cucumber, and tomatoes can also infect potatoes.
There are three main types of symptoms associated with potato virus diseases. One common symptom is mosaic patterns on the leaves, where chlorophyll is unevenly distributed, resulting in yellowish or greenish mottling. In severe cases, the leaves may shrink, the plant becomes stunted, and the veins and leaves may become transparent. Another type involves necrotic spots on the leaves, petioles, shoots, and stems, often appearing as brown lesions. In extreme cases, the entire leaf may wither or curl inward along the midrib, becoming hard and leathery. In some cases, the leaflets may even form tubular shapes. Compound infections can lead to more severe conditions like potato plaque necrosis.
PVX causes light mosaic symptoms, sometimes with mottled or ring-shaped spots. Its virions are linear, measuring 480–580 nm in length, and it has a broad host range, primarily affecting Solanaceae plants. It can be diluted up to 1,000,000 times and remains viable for over a year in vitro at temperatures above 68°C. PVS causes mild leaf shrinking or mosaic symptoms. Its virions are linear, 650 nm long, and it has a narrow host range, infecting only a few Solanaceae species. It can be diluted up to 10 times and survives in vitro for 3–4 days. PVA causes mild mosaic symptoms, with virions 730 nm long and a limited host range. It can be diluted up to 10 times and survives for 12–18 hours in vitro.
PVY causes severe mosaic or necrotic streaks on leaves. Its virions are linear, 730 nm long, and it infects many Solanaceae plants. It can be diluted up to 1000 times and survives for 1–2 days in vitro. PLRV causes leaf rolling and has spherical virions, 25 nm in diameter. It infects mainly Solanaceae plants and can be diluted up to 10,000 times. It survives for 12–24 hours at room temperature and up to four days at 2°C. TMV can also infect potatoes.
The transmission of these viruses occurs mainly through aphids and sap contact. Poor field management, heavy infestations of aphids, and high temperatures (above 25°C) can weaken the plant’s resistance and promote the spread of the virus. Some potato varieties show resistance to certain viruses, but most do not. Virus-free seed potatoes, produced through heat treatment and shoot tip culture, are effective in reducing viral infection. Using virus-free seeds ensures that the initial planting material is free from viruses, significantly improving crop quality and yield.
Control measures include early harvesting of seedlings, avoiding aphid transmission, and using resistant varieties. Insecticides may help control aphids, but they are not always effective against all transmission routes. Other practices, such as proper cultivation techniques, avoiding nitrogen-rich fertilizers, and increasing phosphorus and potassium levels, can also help reduce the risk of infection.
In the early stages of infection, spraying antiviral agents such as 0.5% mushroom proteoglycan (diluted 300 times), 20% virus A wettable powder (500 times), 5% bacteria water agent (5.0 times), 1.5% disease Ling K emulsion (1000 times), or 15% virus will WP (500–700 times) can be effective. These methods, combined with good agricultural practices, are essential in managing viral diseases in potato crops.
Matcha Powder
Matcha, originated from China, is finely ground powder of specially grown and processed green tea.
It is special in two aspects of farming and processing: The green tea plants for matcha are shade grown for about three weeks before harvest, and the stems and veins are removed in processing.
The traditional Chinese tea ceremony centers on the preparation, serving, and drinking of matcha. In modern times, matcha also has come to be used to flavour and dye foods such as mochi and soba noodles, green tea ice cream,etc.
It`s a special form of green tea:
Matcha literally means powdered tea." When you order traditional green tea, components from the leaves get infused into the hot water, then the leaves are discarded. With matcha, you`re drinking the actual leaves, which have been finely powdered and made into a solution, traditionally by mixing about a teaspoon of matcha powder with a third cup of hot water (heated to less than a boil), which is then whisked with a bamboo brush until it froths.
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